If you are like me you probably are installing some freeware apps and also some new beta software to try. You have no doubt ran across an installation error or corruption, either adding or removing these programs. Microsoft has release a tool that will help fix corrupted installs or removals.
The Microsoft Installer Cleanup Utility is located here (http://support.microsoft.com/kb/290301/)
Here is the summary from Microsoft
Microsoft has updated the Windows Installer CleanUp Utility. With the Windows Installer CleanUp Utility, you can remove a program’s Windows Installer configuration information. You may want to remove the Windows Installer configuration information for your program if you experience installation (Setup) problems. For example, you may have to remove a program’s Windows Installer configuration information if you have installation problems when you try to add (or remove) a component of your program that was not included when you first installed your program.